IP telephone and IP adaptor

ABSTRACT

When one of two IP telephones that are maintaining a call receives a TV camera connection request, the IP telephone obtains a URI of an IP TV camera service from a resource record of the opposing terminal. Then, the IP telephone delivers the URI of the IP TV camera service to an IP TV camera adaptor of its own IP telephone in order to make a video communication request. The resource record of the opposing terminal is associated with a telephone number of the opposing IP telephone, the record being obtained by connecting to a DNS server. The IP TV camera adaptor connects a call, via the IP telephone, to an IP TV camera adaptor of the opposing terminal, using the URI of the IP TV camera service of the opposing terminal and performs video image communication.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an IP telephone and an IP telephonecall method that enable a voice call over the Internet.

2. Description of Related Art

In recent years, various forms of IP telephone services that employ theVoIP (Voice over Internet Protocol) technology are provided (e.g.,Related Art 1). As an example of the IP telephone services, an SIPserver on an IP network connects a call, according to the SIP (SessionInitiation Protocol), between an IP telephone at a caller terminal andan IP telephone at a receiver terminal. After the call is connected, theIP telephones exchange voice packets via the IP network, in order torealize the real-time telephone call.

In addition, IP TV telephones that can transmit image data together withvoice data are being developed. For example, an integrated IP TVtelephone, which is equipped with components such as a display, camera,IP telephone, and codec, has been introduced. Another type of IP TVtelephone is a set-top box type IP telephone that includes a camera,microphone, and codec, the telephone functioning as an IP TV telephoneby connecting to a TV.

[Related Art 1] Japanese Patent Laid-open Application 2003-219027

However, an IP telephone not having such a TV telephone function cannottransmit image data, along with voice data, to an opposing party.Therefore, it is impossible for both parties to exchange video imagesgenerated at its own side, so that the video images are displayed on aTV at the opposing party.

SUMMARY OF THE INVENTION

The present invention addresses the above-described problem. The purposeof the invention is to provide an IP telephone, IP adaptor, and IPtelephone system that enable an IP telephone not having a TV telephonefunction to transmit a video image to a display apparatus of an opposingterminal in real-time, the video image being generated by a cameraapparatus of the transmitting terminal, and to display received videoimage transmitted from an opposing party using a display apparatus atits own terminal in real-time.

In the present invention, when one of two IP telephones maintaining acall receives a TV camera connection request, the IP telephone obtains aURI of an IP TV camera service from a resource record of the opposingterminal. Then, the IP telephone delivers the URI of the IP TV cameraservice to an IP adaptor of its own IP telephone in order to make arequest for video communication between IP adaptors of both sides. Theresource record of the opposing terminal is associated with a telephonenumber of the opposing IP telephone, the record being obtained byconnecting to a DNS server.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, with reference to the noted plurality of drawings by wayof non-limiting examples of exemplary embodiments of the presentinvention, in which like reference numerals represent similar partsthroughout the several views of the drawings, and wherein:

FIG. 1 is a block diagram illustrating an IP telephone according to anembodiment of the present invention;

FIG. 2 illustrates a network configuration to which the IP telephone ofFIG. 1 is applied;

FIG. 3 illustrates a configuration of a converted telephone number towhich a domain is attached;

FIG. 4 illustrates an example of an NAPTR resource recode;

FIG. 5 is a block diagram illustrating an IP TV camera adaptor accordingto the embodiment of the present invention;

FIG. 6 is a flowchart illustrating the first half of a process forgenerating and executing a call at a caller terminal;

FIG. 7 is a flowchart illustrating the second half of the processgenerating and executing the call at the caller terminal; and

FIG. 8 is a flowchart of the IP TV camera adaptor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of an IP telephone having an IFAX function according to thepresent invention are explained in the following, in reference to theabove-described drawings.

FIG. 1 is a functional block diagram illustrating the IP telephoneaccording to an embodiment of the present invention. As shown in FIG. 1,the IP telephone has a configuration that enables voice calls via theInternet using the IP telephone function, as well as image communicationvia the Internet using the IFAX function. The IFAX function does notneed to be installed to the IP telephone according to the presentinvention.

Within the IP telephone, units such as scanner 11, operation panel 12,LAN controller 13, printer 14, voice compression/expansion unit 15,modem 16, and handset 17 are connected to CPU 10 via a bus. In addition,the IP telephone further includes memory media such as ROM 18, RAM 19,and removable memory 20.

Scanner 11 is a unit that scans a document and captures the image in anelectronic data format. Operation panel 12 is a unit that includes adisplay and operation buttons, one of which is a start button that givesa command for starting an operation for IP TV camera communication. Theoperation button includes another start button that gives a command forstarting functions such as scanner function, IFAX function, and copyfunction. In addition, soft buttons displayed on the display can alsofunction as operation buttons. LAN controller 13 has an interfacefunction that interfaces and exchanges data with the LAN, by physicallyconnected to LAN, according to the LAN protocol. Data being exchanged bythe IP telephone via the Internet is transmitted to the Internet orretrieved from the Internet by LAN controller 13. Printer 14 is a unitthat prints out printed data, the data being output from a print commandof CPU 10. The copy function is performed by capturing an image atscanner 14 and outputting a printout at printer 14. Printer 14 alsoperforms one of IFAX functions, that is, to output a received image as aprintout. Voice compression/expansion unit 15 includes a DSP (DigitalSignal Compressor) that expands voice data (compressed data) retrievedfrom LAN controller 13. Modem 16 is a unit that transmits and receivessignals to/from the public phone line. Handset 17 includes a speaker anda microphone. The apparatus also includes an off-hook/on-hook detectioncircuit that detects whether handset 17 is in the off-hook/on-hookstatus and notifies the detection result to CPU 10 (not shown in thefigures). ROM 18 stores application programs for functions of the IPtelephone, including the IP telephone function, IFAX function, scannerfunction, and copy function. In particular, in order to execute eachabove-described function, CPU 10 executes a command for a program readfrom ROM 18, and controls the operation of each unit. RAM 19 is a workarea for CPU 10 to execute each process. Removal memory 20 includesmemory media such as CD, FD(R), etc.

FIG. 2 illustrates a network configuration to which the IP telephone isapplied. IP telephone 100 (110) is connected to LAN 101 (111) to enablean access to Internet 103 via LAN 101 (110) and router 102 (112).

DNS server 104, SIP server 105, and mail server 106 are provided onInternet 103. DNS server 104 functions as an ENUM (Telephone NumberMapping) DNS that employs the ENUM protocol associating a telephonenumber with a resource on the Internet.

SIP server 105 is a server that assists processes such as establishing asession on the network, according to SIP (Session Initiation Protocol).In this embodiment, SIP server 105 connects a call between the callerterminal and the receiver terminal.

Mail server 106 has a POP server configuration. For example, mail server106 includes a mailbox of IP telephone 110 that receives, via theInternet, e-mail having the e-mail address of IP telephone 110 in the“to” field, and stores the e-mail. Upon receiving a reception requestfrom IP telephone 110, the e-mail stored in the mailbox is downloaded tothe IP telephone 110.

The following briefly explains a system in which a telephone number isconverted into a URI at DNS server 104.

The ENUM searches for a DNS using a telephone number as a key, based onthe E.164 recommendation (international agreement for telephone numbersby ITU-T). The ENUM provides a system in which one or more availableapplications, corresponding to the E.164 number, are obtained in the URI(Uniform Resource Identifier) format.

ENUM DNS stores data for each telephone number that is converted andattached to a domain (hereafter referred to as domain-form telephonenumber). Data is stored as a type of a resource record (RR) called NAPTR(Naming Authority Pointer) (hereafter referred to as NAPTR resourcerecord).

One or more NAPTR resource records can be registered for a domain-formtelephone number. Therefore, when searching for an ENUM DNS using thedomain-form telephone number, it is possible to receive a plurality ofNAPTR resource records.

FIG. 3 illustrates a configuration of the NAPTR resource record. In thefigure, a telephone number of the terminal is converted into adomain-form number (30) according to a predetermined rule. Inparticular, the telephone number is reversed in order, and dots “.” areinserted after each numeral. At the end of the reversed number,“e164.arpa”, which is a domain name of ENUM DNS (104), is added. In thenext line of the domain-form telephone number (30), class (31), resourcerecord type (32), priority degree among NAPTR resource records (33, 34),flag (35), service contents (36, 37), substitute character string (38),URI scheme (39), and URI (40). URI (40) illustrates address informationin case the terminal having the telephone number (30) uses the servicedescribed in the service contents (36, 37). In other words, the NAPTRresource record can specify the kind of service by the service contents(36, 37), and URI (40) can specify the address when the service is used.ENUM DNS (104) can register a plurality of NAPTR resource records inassociation with the domain-form telephone number (30) of its own.

FIG. 4 illustrates an example of registering four NAPTR resource recordsin association with the telephone number “81-03-5434-5678”. An IPtelephone service is assigned to the first NAPTR resource record, anIFAX service to the second, a file transport service to the third, andan IP TV camera service to the fourth. When the NAPTR resource record ofFIG. 4 is provided for the telephone number of IP Telephone 110, URI(40) included in the fourth NAPTR resource record indicates an addressof IP TV camera adaptor 133 specified by the user of IP telephone 110.

In this embodiment, camera 121 and TV 122 are provided in an area whereIP telephone 100 is located. Camera 121 and TV 122 are connected to LAN101 (Internet 103) via IP TV camera adaptor 123. Similar configurationis provided in the area where another IP telephone 110 is located. Inparticular, camera 131 and TV 132 are provided so that they can beconnected to LAN 111 (Internet 103) via IP TV camera adaptor 133.

FIG. 5 is a functional block diagram of IP TV camera adaptor 123. ROM141 RAM 142, TV camera interface 143, video image encoder and decoder145, LAN controller 146 are connected to CPU 140 via a bus or the like.ROM 141 stores an application program that performs an IP TV cameracommunication. CPU 140 executes a command described in a program, whichis read from ROM 141, and controls on IP TV camera communication (laterdescribed). In this example, CPU 140 connects a call to an opposing IPTV camera adaptor 133 according to the SIP. A video output terminal ofcamera 121 and a video input terminal of TV 122 are physically connectedto TV camera interface 143 via a cable or the like. Video image encoderand decoder 145 performs encoding and decoding of a video image. In thisexample, video image encoder and decoder 145 performs encoding anddecoding according to MPEG 4. LAN controller 146 has a function thatinterfaces with LAN 101, is physically connected to LAN 101, andexchanges data in accordance with the LAN protocol.

In this embodiment, IP telephone 100 and IP telephone 110 have the sameconfiguration. Also, IP TV camera adaptor 123 and the IP TV cameraadaptor 133 have the same configuration. Therefore, the same numericalcharacters are applied to parts having the same configuration.

The following illustrates an operation in which a receiver terminaldisplays a video image generated at a caller terminal, while maintaininga voice call between both terminals using IP telephones.

FIGS. 6 and 7 are flowcharts illustrating a process at the callerterminal. The illustration uses IP telephone 100 as the caller terminaland IP telephone 110 as the receiver terminal, as shown in FIG. 2. Whenplacing a call from IP telephone 100, the user removes handset 17 fromthe body of the apparatus and inputs the telephone number of receiver IPtelephone 110 from operation panel 12.

When caller IP telephone 100 detects that handset 17 is in the off-hookstate (S101) and recognizes that the telephone number is input (S102),the input telephone number is converted into a domain form so as to besearchable by the ENUM DNS (S103). For example, when the telephonenumber of receiver IP telephone 110 is “81-03-5434-5678”, thedomain-form telephone number is “8.7.6.5.4.3.4.5.3.1.8.e164.arpa”. CPU10 makes a request to DNS server 104 for a NAPTR resource record searchusing the domain-form telephone number as a key (S104). It is preferablethat the address of DNS server 104 is pre-registered in caller IPtelephone 100.

DNS server 104 searches the database using the specified domain-formtelephone number as the key. When the receiver terminal has alreadyregistered the service in the NAPTR resource record of DNS server 104,the corresponding NAPTR resource record is retrieved and transmitted tothe requester (caller IP telephone 100).

Upon receiving the NAPTR resource record from DNS server 104, caller IPtelephone 100 recognizes that the NAPTR resource record exists (S105).Therefore, receiver IP telephone 110 obtains the service informationregistered in the NAPTR resource record of DNS server 104, and storesthe information in the work area of RAM 19 (S106). For example, whenreceiver IP telephone 110 has registered 4 NAPTR resource records asshown in FIG. 4, such record contents are stored.

On the other hand, when the NAPTR resource record of DNS server 104 isnot registered, an error process is performed, indicating that therecord does not exist (S108). For example, “error” may be displayed onoperation panel 12.

Next, CPU 10 analyzes the obtained NAPTR resource record and determineswhether the IP telephone service is registered (S107). In case ofobtaining the NAPTR resource records shown in FIG. 4, for example, thefirst NAPTR resource record service contents (36) describes <sip>, andURI (40) describes <iptel>. In this embodiment, it is recognized thatservice contents (36) describing <sip> and URI (40) including <iptel>indicate an IP telephone service.

Therefore, in this case, caller IP telephone 100 determines that the IPtelephone service is available at receiver IP telephone 110. However,the URI information is not sufficient enough to determine what kinds ofservices are actually provided in the terminal, which is connected usingthe URI. Therefore, as an alternative configuration, when it isdetermined that the IP telephone service is not provided in theterminal, after connecting to the same using the URI, the callerterminal may connect to another URI included the NAPTR resource recorduntil it is connected to a terminal having the desired IP telephoneservice.

When none of the URIs included in the NAPTR resource records supportsthe IP telephone service, the control moves to step S108 to perform anerror process. Instead of connecting to all of the URIs, when <sip> isnot included in service content (36) in any of the NAPTR resourcerecords, the control may directly move to the error process so as tosave time for the error process.

Next, caller IP telephone 100 establishes a call to the receiverterminal via SIP server 105 (S109). The call connecting processaccording to the SIP may include the following steps. Caller IPtelephone 100 first transmits an INVITE message to SIP server 105, themessage including the information of receiver IP telephone 110. Theinformation about receiver IP telephone 110 included in the INVITEmessage can be obtained from the NAPTR resource record stored at stepS106. When using the NAPTR resource record in FIG. 4, SIP URI(iptel@ifax2.abc.com) is used as the destination information of receiverIP telephone 110, the information being described in the first NAPTRresource record that specifies the IP telephone service.

Upon receiving the INVITE message, SIP server 105 transmits the INVITEmessage to receiver IP telephone 110, requesting a connection. ReceiverIP telephone 110's SIP URI (iptel@ifax2.abc.com) is used as thedestination for the INVITE message.

Upon receiving the INVITE message (requesting the connection), receiverIP telephone 110 returns a message, to the caller terminal, allowing theconnection via SIP server 105. Upon receiving the message allowing theconnection, caller IP telephone 100 transmits an ACK message to receiverIP telephone 110 via SIP server 105. Upon receiving the ACK message fromcaller IP telephone 100, receiver IP telephone 110 returns “Ringing”(indicating a ringing status) to caller IP telephone 100 and transmits asounding request to the handset.

Upon receiving “Ringing”, caller IP telephone 100 sounds a ring tonefrom a speaker of handset 17. This ringing status continues until thereceiver's handset 17 is taken off the hook (S110), or the caller'shandset 17 is put back on the hook (S111). When the caller's handset 17is put back on the hook, it indicates that the user at caller IPtelephone 100 put handset 17 back to the apparatus. Therefore, theprocess is terminated.

When the user at receiver IP telephone 110 picks up handset 17responding to the ringing phone to allow the operation at the terminal,receiver IP telephone 110 transmits an “OK” message to the callerterminal via SIP server 105, the message notifying that the voice callis now available. When the caller terminal returns an “ACK” message, thevoice call is initiated.

When the caller and receiver terminals 100 and 110 are connected, bothterminals perform direct communication without SIP server 105 (S112).The exchange of voice data is performed by the UDP using the RTP. Voicedata input from the microphone of handset 17 is compressed by voicecompression/expansion unit 15. CPU 10 transmits voice packets toInternet 103 via LAN 101, by inserting a task interruption everypredetermined time period (e.g., every 20 msec). The IP header of thevoice packet includes a sender IP address (caller terminal) and adestination IP address (receiver terminal). The RTP header sets timestamp information for controlling the order of the voice data.

The following illustrates the IP TV camera service in which a userhaving a voice call at caller IP telephone 100 enables a user atreceiver IP telephone 110 to display a video image on TV 132 of thereceiver terminal, the video image being generated by camera 121 of thecaller terminal.

The user at caller IP telephone 100 presses the start button forstarting the IP TV camera service, button being located in the operationpanel 12. The start button can be a switch button specially designatedfor the IP TV camera service, or the button can be a soft buttondisplayed on the display.

When CPU 10 of caller IP telephone 100 detects that the start button forthe IP TV camera service is pressed during an IP telephone, CPU 10recognizes that the IP TV camera communication request has been made(S113). When handset 17 of the caller terminal is put back on the hook,without the start button for IP TV camera communication being pressedduring the IP call (S121), or when handset 17 of the receiver terminalis put back on the hook (S122), the voice call is terminated (S123).

Upon detecting the IP TV camera communication request, CPU 10 of thecaller terminal determines whether receiver IP telephone 110 (with whichthe voice call is performed) supports the IP TV camera service (S114).Therefore, CPU 10 retrieves the NAPTR resource record (obtained at stepS106) from a predetermined address stored in RAM 19, in order to checkwhether the IP TV camera service is included in any of the NAPTRresource records.

In this embodiment, when service contents (36) in the NAPTR resourcerecord describes <sip>, and URI (40) includes a character codes<ipTVcamera>, it is recognized that the terminal having the URI supportsthe IP TV camera service.

Similar to the case of the IP telephone service described above, the URIinformation is not sufficient enough to determine what kinds of servicesare actually provided in the terminal, which is connected using the URI.Therefore, as an alternative configuration, when it is determined thatthe IP TV camera service is not provided in the terminal, afterconnecting to the same using the URI, the caller terminal may connect toanother URI included in the NAPTR resource record until it is connectedto a terminal having the desired IP TV camera service.

In the current IETF regulation, “SIP” is the only real-timecommunication service. Therefore, for specifying a real-timecommunication service including an IP telephone service and an IP TVcamera service, <sip> is described in service content (36) of the NAPTRresource record. Therefore, the present embodiment checks up to URI (40)to determine whether the service content is IP telephone service or IPTV camera service. However, when a regulator such as IETF sets aregulation in the future, providing a specific character codedescription of the IP TV camera service, instead of <sip>, in servicecontent (36) of the NAPTR resource record, the determination (of whetherthe IP TV camera service is supported) can be made by recognizing such acharacter code.

When none of the URIs included in the NAPTR resource records supportsthe IP TV camera service, the control moves to step S115 to perform anerror process. Instead of connecting to all of the URIs, when <sip> isnot included in service content (36) in any of the NAPTR resourcerecords, the control may directly move to the error process so as tosave time for the error process.

Next, CPU 10 of caller IP telephone 100 obtains the URI of IP TV cameraadaptor 133 (of the receiver terminal), which is an adaptor connected tocamera 131 and TV 132 (S116). In the example shown in FIG. 4, CPU 10obtains the SIP URI (ipTVcamera@ipTVcameara.abc.com) included in thefourth NAPTR resource record.

Further, caller IP telephone 100 connects to caller IP TV camera adaptor123 via LAN 101 (S117). The connection to the IP TV camera adaptor 123is performed by using an IP address of IP TV camera adaptor 123 (of thecaller), which is stored, in advance, in caller IP telephone 100. Then,IP telephone 100 gives the URI of the IP TV camera adaptor 133 (theadaptor of the receiver's camera 131 and TV 132) to IP TV camera adaptor123 in order to start the video communication between IP TV cameraadaptors 123 and 133 (adaptor 133 having the desired URI) (S118).

FIG. 8 is a flowchart of one IP TV camera adaptor 123. IP TV cameraadaptor receives a command for the IP TV camera communication when theURI of the opposing IP TV camera adaptor 133 is specified by IPtelephone 100 (S200). IP TV camera adaptor 123 connects a call to theopposing IP TV camera adaptor 133 via SIP server 105 (S201). After thecall connection is made, the video images being generated by bothcameras 121 and 131 are exchanged by adaptors 123 and 133 (S202). The IPpackets exchanged between adapters 123 and 133 have an IP address ofadaptor 123 or 133 as the destination IP address in the IP header. Also,similar to the case of the VoIP, RTP header is added to the image datainstead of the voice data.

When camera 121 is turned on at the caller side, the video imagegenerated by camera 121 is input to the corresponding IP TV cameraadaptor 123 as a video signal. IP TV camera adaptor 123 captures thevideo signal from TV camera interface 143. The video image encoder anddecoder 145 encodes and compresses the video data. Then, CPU 140generates an IP packet including the encoded video image data. Theheader of the IP packet includes an IP address of the opposing IP TVcamera adaptor 133 as a destination IP address. The IP address of theopposing IP TV camera adaptor 133 is obtained by specifying the domainname of the URI from DNS server 104. However, the IP address can beobtained and used when connecting the call according to the SIP. The IPpacket including the video image generated by a camera 121 istransmitted to the Internet 103 from LAN controller 146, via LAN 101 androuter 102.

The IP packets transmitted to the Internet 103 by the IP TV cameraadaptor 123 is routed into LAN 111 by router 112 and retrieved by IP TVcamera adaptor 133.

IP TV camera adaptor 133 retrieves the video data from the IP packets(captured by LAN controller 146) and decodes the data using video imageencoder and decoder 145. The decoded video data is then provided to avideo image input terminal of TV 132 as the video signal. Therefore, thevideo image generated by the caller terminal camera 121 is displayed inreal-time on TV 132 at the receiver terminal.

Similarly, the video image generated by a camera 131 of IP telephone 110is displayed on TV 122 via opposing IP TV camera adaptor 123.

As shown in FIG. 7, when IP telephone 100 detects the on hook status ofhandset 17 of the receiver terminal or the caller terminal, IP telephone100 determines the call is terminated (S119) and transmits a completionnotification to its own IP TV camera adaptor 123 via LAN (S120).

As shown in FIG. 8, upon receiving the completion notification from IPtelephone 100 (S203), IP TV camera adaptor 123 terminates the IP TVcamera communication.

Accordingly, when IP telephone 100 gives the URI of the opposing IP TVcamera adaptor 133 to its own IP TV camera adaptor 123 and requests theconnection, the IP TV camera adaptor 123 and IP TV camera adaptor 133autonomously establish a mutual connection and exchange video data.Therefore, it is possible for both sides to display video images of theopposing side, in real-time, during the voice call using the IPtelephone.

In the above-described description, when caller IP telephone 100receives an input of TV camera connection request, caller IP TV cameraadaptor 123 makes a call connection request to receiver IP TV cameraadaptor 133. However, the present invention is not limited to the aboveexample. Similar connection can be made, conversely, when receiver IPtelephone 110 receives an input for the TV camera connection request. Inparticular, when a TV camera connection request is input to IP telephone110, the telephone number of IP telephone 100 is converted into adomain-form, in order to obtain a NAPTR resource record corresponding tothe telephone number from DNS server 104. Then, it is determined whetherthe opposing side (caller side) supports the IP TV camera service. Whensupported, a URI of the IP TV camera service (URI for IP TV cameraadaptor 123) is obtained so that the IP TV camera adaptor 133 canconnect a call to IP TV camera adaptor 123 according to the SIP.

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to exemplary embodiments, it is understood that the wordswhich have been used herein are words of description and illustration,rather than words of limitation. Changes may be made, within the purviewof the appended claims, as presently stated and as amended, withoutdeparting from the scope and spirit of the present invention in itsaspects. Although the present invention has been described herein withreference to particular structures, materials and embodiments, thepresent invention is not intended to be limited to the particularsdisclosed herein; rather, the present invention extends to allfunctionally equivalent structures, methods and uses, such as are withinthe scope of the appended claims.

The present invention is not limited to the above-described embodiments,and various variations and modifications may be possible withoutdeparting from the scope of the present invention.

This application is based on the Japanese Patent Application No.2004-103927 filed on Mar. 31, 2004, entire content of which is expresslyincorporated by reference herein.

1. An IP telephone, comprising: an interface configured to be connectedto an ENUM (Telephone Number Mapping) server and to an IP adaptor via anetwork, the IP adaptor being arranged in the same LAN as the IPtelephone, the ENUM server storing a NAPTR (Naming Authority Pointer)resource record associated with a domain formed telephone number of adestination IP telephone, the NAPTR resource record including a URI(Uniform Resource Identifier), the IP adaptor being connected to acamera and to a display, the camera capturing an image of a user of theIP telephone, the display displaying an image of a user of thedestination IP telephone; an input device configured to input atelephone number of the destination and to instruct starting of an IP TVcamera service; and a controller configured to: transform the inputtelephone number into the domain formed telephone number; obtain, fromthe ENUM server, the NAPTR resource record associated with the domainformed telephone number; perform a voice communication with thedestination IP telephone via the network; detect an instruction to startthe IP TV camera service during the voice communication; and transmit,to the IP adaptor, the URI included in the obtained NAPTR resourcerecord and a request for a video communication with an IP adaptor of thedestination IP telephone, when the controller detects the instruction tostart the IP TV camera service during the voice communication, the IPadaptor connects with the IP adaptor of the destination IP telephone bycalling the destination IP telephone using the URI, encodes the imagecaptured by the camera and transmits the encoded image to the IP adaptorof the destination IP telephone, decodes the image received from the IPadaptor of the destination IP telephone and displays the decoded imageon the display.
 2. The IP telephone according to claim 1, wherein acontroller obtains, from the ENUM server, a plurality of NAPTR resourcerecords associated with the domain formed telephone number of thedestination IP telephone.
 3. The IP telephone according to claim 2,wherein, when the voice communication is performed, the controllersearches for the NAPTR resource record including the URI for the voicecommunication, from the plurality of the obtained NAPTR resourcerecords.
 4. The IP telephone according to claim 2, wherein, when therequest for the video communication is transmitted to the IP adaptor,the controller searches for the NAPTR resource record including the URIfor the video communication, from the plurality of the obtained NAPTRresource records.
 5. The IP telephone according to claim 1, whereinduring the voice communication with the destination IP telephone, thecontroller transmits, to the IP adaptor, the URI included in theobtained NAPTR resource record and the request for the videocommunication with a IP adaptor of the destination IP telephone.
 6. AnIP adaptor, comprising: a first interface configured to be connected toa IP telephone, the IP telephone performing a voice communication with adestination IP telephone, the IP telephone being connected to an ENUM(Telephone Number Mapping) server, the ENUM server storing a NAPTR(Naming Authority Pointer) resource record associated with a domainformed telephone number of the destination IP telephone, the NAPTRresource record including a URI (Uniform Resource Identifier), the IPtelephone obtaining, from the ENUM server, the NAPTR resource recordassociated with the domain formed telephone number of the destination IPtelephone; a second interface configured to be connected to a camera andto a display, the camera capturing an image of a user of the IPtelephone, the display displaying an image of a user of the destinationIP telephone; a video image encoder and decoder configured to encode anddecode the image; and a controller configured to: receive, from the IPtelephone, the URI included in the NAPTR resource record and a requestfor a video communication with an IP adaptor of the destination IPtelephone; connect with the IP adapter of the destination IP telephoneby calling the destination IP telephone using the received URL; performthe video communication with the IP adaptor of the destination IPtelephone using the URI; transmit, to the IP adaptor of the destinationIP telephone, the image encoded by the video image encoder and decoder,the image captured by the camera; and display, on the display, the imagedecoded by the video image encoder and decoder, the image received fromthe IP adaptor of the destination IP telephone.
 7. A method for making acall using an IP telephone, the IP telephone being connected to an ENUM(Telephone Number Mapping) server and to an IP adaptor via a network,the IP adaptor being arranged in the same LAN as the IP telephone, theENUM server storing a NAPTR (Naming Authority Pointer) resource recordassociated with a domain formed telephone number of a destination IPtelephone, the NAPTR resource record including a URI (Uniform ResourceIdentifier), the IP adaptor being connected to a camera and to adisplay, the camera capturing an image of a user of the IP telephone,the display displaying an image of a user of the destination IPtelephone, the call method comprising: inputting, at the IP telephone, atelephone number of the destination and an instruction to start an IP TVcamera service; transforming, at the IP telephone, the input telephonenumber into the domain formed telephone number; obtaining, from the ENUMserver, the NAPTR resource record associated with the domain formedtelephone number; performing, at the IP telephone, a voice communicationwith the destination IP telephone via the network; detecting aninstruction to start the IP TV camera service during the voicecommunication; transmitting, from the IP telephone to the IP adaptor,the URI included in the obtained NAPTR resource record and a request fora video communication with an IP adaptor of the destination IP telephonewhen the instruction for starting the IP TV camera service during thevoice communication is detected; connecting, with the IP adaptor of thedestination IP telephone by calling the destination IP telephone usingthe URI; and encoding the image captured by the camera and transmittingthe encoded image to the IP adapter of the destination IP telephone,decoding the image received from the IP adaptor of the destination IPtelephone, and displaying the decoded image on the display.